WordPress has made Seo easy and trendy. I personally suggest you to install and activate WordPress SEO by Yoast because it comes with maximum features.
WordPress SEO by Yoast contains,
- Website meta-title and description
- XML Sitemap
- Meta Robots
- Ping Yahoo/Bing/Google
- Include and exclude specific pages and post
- WordPress post and pages Seo analysis
- 301 redirection and canonical URL
- One click import and export settings
Above features is available in current plugin but with the passage of time plugin will be update with additional features.